Valve control of fluid flow, both gases and liquids, is an old and well populated art. Numerous styles of soft valve are known, the following are representative of current art. Collectively, arranged chronologically, each with a short description, they provide in their entireties, a background for understanding the current teachings regarding curved pliant film valves.
Snow, U.S. Pat. No. 3,955,594 (1976), “Pressure Operated Valve Systems” describes a relatively simple pinch valve formed as a normally closed elastic collar which blocks flow in a steel pipe. When sufficient pressure is applied to a fluid material like unset concrete the closed sleeve-like collar is forced open and a flow passageway created, the only control to open and close the valve is the pressure applied by the fluid itself. There is no provision for one-way control, sufficient pressurized backflow can open the passageway as easily as forward flow.
Atkinson, U.S. Pat. No. 5,010,925 (1991), “Normally Closed Duckbill Valve Assembly” is representative of a large category of one-way valves characterized by their descriptive duckbill shaped lips. Numerous variations exist derived from the size, shape and other attributes of design. Here, novelly shaped valve lips pivot outwardly on comparatively narrow stalks to open a relatively unrestrictive passageway to fluid flow. Common problems with such designs are the narrow sealing area afforded by the lips which wear rapidly due to flutter movement, damaged to the lips by fluid content, and lip seals that are prone to clogs contributing to leakage.
Drew, U.S. Pat. No. 5,144,986 (1992), “One Way Flow Device” describes a class of simple film valves sometimes seen in novelties such as balloons. Drew teaches a film attached to the sides of a fluid channel so as to allow only flow through a hole in the film. The film has sufficient longitudinal movement so that when flow is in a forward direction it moves the hole to the channel center but when flow is reversed the film with the hole is pushed against a channel wall and effectively closed. Due to the restrictive nature of the hole as the only passage for flow, clogging and poor seals are common with this design.
Jang, U.S. Pat. No. 5,755,263 (1998), “Backward Flow Prevention Device” describes a variation of a duckbill design best described as a windsock duckbill. A truncated cone of flexible material is mounted on a capped pipe with side holes as fluid outlets. The windsock tube trails off downstream in the channel, guiding all flow from the outlet to the far end of the cone where it emerges back into the channel. When reverse flow occurs the sock collapses and is bunched up at off-angle to the pipe thereby preventing the backflow from entering the outlet holes. A design having limited if functional applications.
Nickels, U.S. Pat. No. 6,536,631 (2003), “Sealed Fluid Dispensing Device” is representative of art where foam collars act as valves for handheld dispensers, the distinctions between numerous patented designs is subtle. They generally operate, as here, by forcing liquid from a pressure operated reservoir, up a channel to emerge from a fixed body clad with an elastic membrane. Under pressure the fluid separates a portion of the membrane from the body to form a passageway to a top outlet where the fluid is released for distribution. Absent fluid pressure the membrane closes on the body once again and seals off the temporary fluid channel. A useful technique having expanded the art through many manifestations.
Persson, U.S. Pat. No. 6,810,914 (2004), “Method and Arrangement to Accomplish a One-Way Flow” describes a plastic bag deployed in a sewer pipe to prevent backflow while offering minimal interference to continuous sewage outflow. Noting that swinging iron gates and like devices impede flow and often result in disastrous blockage, a flexible elastic bag partially glued to the pipe wall is designed to flatten against the pipe wall during outflow thereby offering minimal resistance but deploys to open and fill with backflow fluid to temporarily block the sewer when reverse flow occurs. It is problematic whether the bag could survive the harsh conditions of sewer flow and sewage content, successfully deploy as contemplated, and avoid creating the very blockages it is designed to alleviate.
Swiss, U.S. Pat. No. 7,306,129 (2007), “One Way Valve Assembly” describes another elastomeric membrane design covering a fixed core where ports allow flowable substances to push the flexible membrane away so as to form a flow path to a dispensing exit. Here, the membrane, when not pushed out by fluid pressure, blocks the ports so as to seal them against any backflow bearing contaminants. Swiss is distinguished from Nickels only by the shape and function of its inner core. In this class of dispensing valves the distinctions are often quite subtle.
Gueret, U.S. Pat. No. 7,594,595 (2009), “Device and Method for Dispensing of a Product” teaches a valve for controlling fluid flow described as a flow reducer which is essentially a foam disc with variously shaped slits through its center where pressurized fluid from a lower reservoir follows these slit routes to exit on the upper foam surface for dispensing. A key feature distinguishing this art is that the foam is permeable to air which allows atmospheric air to enter the reservoir thereby alleviating the buildup of negative reservoir pressure when the squeeze is released. While the device has some valve characteristics, it does require a cap on the foam disc to prevent leakage and evaporation given the foam is porous to fluids.
None of these disclosures individually or in aggregate either describe or suggest a particularly low-cost, reliable, disposable, minimal component, securely sealing one-way valve action that is easy to manufacture. The need for such a securely sealing one-way valve of simple, economical design has yet to be met.